Question

Y=9x^2+126x-74. Find min?

Answer 1

dy/dx=18x+126=0
x=-126/18
x=-7
find d^2y/dx^2
=18
second derivative >0 for x=-7
so function will be minimum at x=-7
y min=9*(-7)^2 +126*(-7)-74
=-515
@Mrhnodri

Answer 2

Thank you :)